4.You currently have an active transaction in your session and have been granted select access to V$TRANSACTIONhttp://www.cndba.cn/hbhe0316/article/108585http://www.cndba.cn/hbhe0316/article/108585

SQL> select xid, status from v$transaction;

XID              STATUS
---------------- ------------------------------------------------
0A000100C1330000 ACTIVE

In which three situations will re-executing this query still return a row but with a different XID indicating a new transaction has started?
A.after successfully executing a TRUNCATE statement followed by a DML statement
B.after successfully executing a CREATE TABLE AS Select statement followed by a SELECT FOR UPDATE statement
C.after successfully executing a CREATE TABLE statement followed by a CREATE INDEX statement
D.after successfully executing a commit or ROLLBACK followed by a DML statement
E.after successfully executing a DML statement following a failed DML statement
F. after successfully executing a commit or ROLLBACK followed by a Select statement
答案:ABDhttp://www.cndba.cn/hbhe0316/article/108585

针对A答案,可以看到A执行后的XID不一样，所以A正确http://www.cndba.cn/hbhe0316/article/108585

SQL> select xid, status from v$transaction;

XID              STATUS
---------------- ------------------------------------------------
03000A00DD0D0000 ACTIVE

SQL> truncate table transaction_table8;

Table truncated.

SQL> insert into transaction_table8 select * from dba_objects;

73552 rows created.

SQL> select xid, status from v$transaction;

XID              STATUS
---------------- ------------------------------------------------
06001600DE0D0000 ACTIVE

针对B答案:

SQL> create table t2 as select * from t1;

Table created.

SQL> select xid, status from v$transaction;

no rows selected

SQL> select * from t2 where id=1 for update;

        ID NAME
---------- ------------------------------
         1 aa

SQL> select xid, status from v$transaction;

XID              STATUS
---------------- ------------------------------------------------
09001F0078160000 ACTIVE

针对D答案http://www.cndba.cn/hbhe0316/article/108585

SQL> create table  transaction_table8 as select * from dba_objects;

Table created.

SQL> insert into transaction_table8 select * from dba_objects;

73552 rows created.

SQL> select xid, status from v$transaction;

XID              STATUS
---------------- ------------------------------------------------
0A001A00C0330000 ACTIVE

SQL> commit;

Commit complete.

SQL> insert into transaction_table8 select * from dba_objects;

73552 rows created.

SQL> select xid, status from v$transaction;

XID              STATUS
---------------- ------------------------------------------------
06000900E40D0000 ACTIVE

由此可见，正确答案ABDhttp://www.cndba.cn/hbhe0316/article/108585http://www.cndba.cn/hbhe0316/article/108585

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